Issue #27392: Document loop.connect_accepted_socket()

Patch by Jim Fulton.

Doc/library/asyncio-eventloop.rst

@@ -461,6 +461,23 @@ Creating listening connections
 
    Availability: UNIX.
 
+.. coroutinemethod:: BaseEventLoop.connect_accepted_socket(protocol_factory, sock, \*, ssl=None)
+
+   Handle an accepted connection.
+
+   This is used by servers that accept connections outside of
+   asyncio but that use asyncio to handle them.
+
+   Parameters:
+
+   * *sock* is a preexisting socket object returned from an ``accept``
+     call.
+
+   * *ssl* can be set to an :class:`~ssl.SSLContext` to enable SSL over the
+     accepted connections.
+
+   This method is a :ref:`coroutine <coroutine>`.  When completed, the
+   coroutine returns a ``(transport, protocol)`` pair.
 
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